Work apparatus

Abstract

A work apparatus includes a drive motor, a tool head including a tool frame, a bearing, a tool shaft and a rotary tool, a frame tube with the proximal end connected to the drive motor and the distal end connected to the tool head, and a drive shaft rotatably inserted through the frame tube for transmitting the rotation of the drive motor to the rotary tool. The rotary tool is accommodated within the tool frame and is rotatable on the tool shaft, when driven by the drive shaft. The tool shaft is journaled by the bearing which is elastically supported by a flexible elastic member disposed coaxially around the bearing and interposed between the bearing and the connection of the tool frame or the frame tube. Undesirable vibrations caused by the rotation of the rotary tool will be effectively hindered from being transmitted to the frame tube.

What is claimed is: 
     
       1. A work apparatus comprising:
 a drive motor; 
 a tool head including a tool frame, a bearing, a tool shaft and a rotary tool, the rotary tool being fixed to the tool shaft and being rotatable on the tool shaft at a rotation frequency, the tool shaft being supported by the bearing within the tool frame; 
 a frame tube having a proximal end connected to the drive motor and a distal end connected to the tool frame of the tool head; 
 a drive shaft rotatably inserted through the frame tube and connecting the drive motor to the tool shaft to rotatably drive the rotary tool; 
 a proximal end of the tool shaft is connected to and extends coaxially with a distal end of the drive shaft 
 a flexible elastic member coaxially disposed surrounding the bearing for elastically supporting the bearing on the connection of the tool frame and the frame tube, and 
 wherein the tool head and the frame tube are connected together to define a vibratory system which has a natural frequency of vibration that is lower than the rotation frequency of the rotary tool. 
 
     
     
       2. A work apparatus as claimed in  claim 1 , wherein the frame tube has a straight portion toward the proximal end connected to the drive motor, and a bent portion toward the distal end connected to the tool frame of the tool head. 
     
     
       3. A work apparatus as claimed in  claim 2 , wherein the rotary tool is a rotary cutter comprised of a cutting line rotatably driven on the tool shaft. 
     
     
       4. A work apparatus as claimed in  claim 3 , wherein the flexible elastic member is a tubular member made of rubber enclosing the bearing which journals the tool shaft on which the rotary tool is rotatable. 
     
     
       5. A work apparatus as claimed in  claim 2 , wherein the rotary tool is a rotary cutter comprised of a cutting blade in a disk shape rotatably driven on the tool shaft. 
     
     
       6. A work apparatus as claimed in  claim 5 , wherein the flexible elastic member is a tubular member made of rubber enclosing the bearing which journals the tool shaft on which the rotary tool is rotatable. 
     
     
       7. A work apparatus as claimed in  claim 2 , wherein the flexible elastic member is a tubular member made of rubber enclosing the bearing which journals the tool shaft on which the rotary tool is rotatable. 
     
     
       8. A work apparatus as claimed in  claim 1 , wherein the rotary tool is a rotary cutter comprised of a cutting line rotatably driven on the tool shaft. 
     
     
       9. A work apparatus as claimed in  claim 8 , wherein the flexible elastic member is a tubular member made of rubber enclosing the bearing which journals the tool shaft on which the rotary tool is rotatable. 
     
     
       10. A work apparatus as claimed in  claim 1 , wherein the rotary tool is a rotary cutter comprised of a cutting blade in a disk shape rotatably driven on the tool shaft. 
     
     
       11. A work apparatus as claimed in  claim 10 , wherein the flexible elastic member is a tubular member made of rubber enclosing the bearing which journals the tool shaft on which the rotary tool is rotatable. 
     
     
       12. A work apparatus as claimed in  claim 1 , wherein the flexible elastic member is a tubular member made of rubber enclosing the bearing which journals the tool shaft on which the rotary tool is rotatable. 
     
     
       13. A work apparatus as claimed in  claim 1 , wherein ends of the flexible elastic member protrude radially inward so as to abut end faces of the bearing.